Yachting Monthly did a detailed test on folding and feathering props in May 2009. If you put ‘The Ultimate Propeller Test’ into their search you can download the article.
Another source of advice is the YBW Forum – suggest you try the PBO section.
A folding or feathering prop will increase your speed under sail, but will do little under engine alone.
As said previously if you change from an aluminium prop be prepared to change your anode mid season.

Good luck,